There are numerous types of collapsible play yards, or other walled structures that keep an infant confined within a limited space, yet which allow freedom of movement so that the infant or small child can play or move around. Permanent type play yards are usually set up at home or at a fixed location and require a substantial amount of time to disassemble and reassemble in order to relocate the play yard. This makes it impractical to move a permanent play yard on a regular basis.
Permanent type play yards tend to be large and cumbersome, making movement or storage of permanent type play yards unwieldy and difficult. As a result, numerous portable play yards have been designed. Play yards must be sturdy in order to contain an infant or young child without collapsing on the child while he or she is playing within the play yard. The play yard must also possess a substantial degree of structural integrity in order to accommodate an infant or child who will frequently pull on or push against the play yard that surrounds him. Further, the play yard must not expose the child or infant to rough or sharp edges where a child may be cut, or to movement of the apparatus, which could pinch a child's hand or foot.
Numerous collapsible or portable play yard designs have been produced over the years in an attempt to achieve a perfect play yard design which provides a sturdy yet portable play yard that does not expose the infant or child to any sharp or rough edges, or other areas in which a child may be injured. Of note amongst these is U.S. Pat. No. 4,688,280 issued to Cohus. The Cohus design employs a central base member to which four rods are pivotally attached. Each of these rods extends to each of the four corners of the foldable play yard assembly. At each of the corners, a vertical post is rotated upwards to provide support for a surrounding fabric enclosure. No structure is provided between any of the four vertical posts along the upper lip of the play yard. As a result, an infant or child can pull on the fabric enclosure thereby lowering the wall of the foldable play yard assembly. The central base member of Cohus allows the four legs to pivot outward and establish the corners of the play yard. No locking mechanism is present to ensure that the legs remain in the desired corner positions.
Another design is seen in U.S. Pat. No. 4,070,716 issued to Satt. The Satt design provides six vertical support legs that support a base and side wall enclosure. The side walls are hinged to collapse inward to the center of the play yard. The hinged portion is formed of a U-shaped piece of material that is riveted to longitudinal bars. The open end of the U is pointed outward. This design ensures vertical stability, and prevents the play yard from being expanded outward by force applied from the inside of the play yard in an outward direction by a child or infant. The U bracket is prevented from collapsing inward towards the center of the play yard solely by the structural strength of the remainder of the play yard. The play yard has a complimentary hinge arrangement at each of the corners in order to allow the play yard to be collapsed. No vertical support is provided at any of the corners of the Satt play yard. The arms of the Satt design are free to collapse inward until resistance is encountered by the remainder of the play yard frame.
Cirillo, U.S. Pat. No. 4,376,318 employs similar U-shaped brackets on opposite ends of a portable play yard design. The Cirillo structure is supported only at the four corners. Similar to Satt, Cirillo allows the outer wall of the play yard to be folded inward in order to collapse the play yard. Cirillo also suggests the possibility of using an independent sleeve that is placed over the hinged portion of the play yard structure in order to prevent the play yard from collapsing by maintaining structural rigidity. U.S. Pat. No. 2,901,755 issued to Wood also employs hinge covers.
Dilner in U.S. Pat. No. 4,811,437 employs a similar U-shaped bracket, but modified the ends of the lateral rod so that the open portion of the U-shaped bracket could be rotated to face downward. Dilner employs a spring loaded assembly in order to ensure that the lateral rods do not separate from the vertical support structure, yet remain rotatable.
None of these inventions provide an easily collapsible play yard that can contain a child with absolutely no threat of the play yard collapsing, or which absolutely guarantees that a child will not gain to access to collapsible or foldable parts which may injure the child.